gc.c: build complete object graph for RGENGC_CHECK_MODE

	* gc.c (reflist_add): return 0 if reference already exists
	* gc.c (allrefs_add): return 1 on newly added references
	* gc.c (allrefs_i): follow references to construct complete object
	  graph. before this patch, RGENGC_CHECK could fail to verify some WB
	  miss issues. [Bug #9226] [ruby-core:58959]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44109 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 4 deletions

diff --git a/gc.c b/gc.c
index 5e560ebf6d..fe006ad81b 100644
--- a/gc.c
+++ b/gc.c
@@ -4164,14 +4164,21 @@ reflist_destruct(struct reflist *refs)
     xfree(refs);
 }
 
-static void
+static int
 reflist_add(struct reflist *refs, VALUE obj)
 {
+    int i = 0;
     if (refs->pos == refs->size) {
 	refs->size *= 2;
 	SIZED_REALLOC_N(refs->list, VALUE, refs->size, refs->size/2);
     }
+
+    for (i=0; i<refs->pos; i++)
+	if (refs->list[i] == obj)
+	    return 0; /* already exists */
+
     refs->list[refs->pos++] = obj;
+    return 1; /* added */
 }
 
 static void
@@ -4215,17 +4222,18 @@ struct allrefs {
     VALUE root_obj;
 };
 
-static void
+static int
 allrefs_add(struct allrefs *data, VALUE obj)
 {
     struct reflist *refs;
 
     if (st_lookup(data->references, obj, (st_data_t *)&refs)) {
-	reflist_add(refs, data->root_obj);
+	return reflist_add(refs, data->root_obj);
     }
     else {
 	refs = reflist_create(data->root_obj);
 	st_insert(data->references, obj, (st_data_t)refs);
+	return 1;
     }
 }
 
@@ -4233,7 +4241,8 @@ static void
 allrefs_i(VALUE obj, void *ptr)
 {
     struct allrefs *data = (struct allrefs *)ptr;
-    allrefs_add(data, obj);
+    if (allrefs_add(data, obj)) /* follow new reference */
+	push_mark_stack(&data->objspace->mark_stack, obj);
 }
 
 static void